**Question:** The percentage of body water is greater in

A. Children
B. Elderly individuals
C. Pregnant women
D. Athletes

**Correct Answer:** B. Elderly individuals

**Core Concept:** Water constitutes a significant proportion of the human body, and its distribution is affected by various factors like age, body composition, and lifestyle choices.

**Why the Correct Answer is Right:** In the context of this question, the percentage of water in the body is primarily influenced by the body's lean mass, which decreases with age. Elderly individuals have a lower lean mass and higher body fat percentage compared to children, pregnant women, and athletes. As a result, the percentage of body water is relatively higher in elderly individuals.

**Why Each Wrong Option is Incorrect:**

A. Children: Although children have a higher lean mass, it is not significantly higher than that of elderly individuals. Thus, the percentage of body water remains relatively lower in children compared to the correct answer, B.

C. Pregnant women: Although pregnant women have a higher body water content due to the increased volume of blood and amniotic fluid, the overall percentage of body water remains lower than that in B.

D. Athletes: Athletes often have a higher lean mass and lower body fat percentage, which leads to a higher percentage of body water compared to the correct answer, B. However, the difference is not as significant as between B and the other options.

**Clinical Pearl:**

The understanding of body water distribution in different age groups is crucial in clinical practice, especially in patients with dehydration, electrolyte imbalances, and fluid management. Elderly patients may require more cautious fluid management as they are more prone to fluid overload-related complications due to their reduced ability to concentrate urine and retain fluids.

**Correct Answer:** B. Elderly individuals

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**Core Concept:** The percentage of body water is primarily influenced by the body's lean mass, which decreases with age.

**Why the Correct Answer is Right:** As age progresses, the lean mass, which includes muscle mass, organs, and bones, decreases, leading to a decrease in the overall percentage of body water. In contrast, elderly individuals have a higher percentage of body water compared to children, pregnant women, and athletes due to their reduced lean mass and higher body fat percentage.

**Why Each Wrong Option is Incorrect:**

A. Children: Although children have a higher lean mass, it is not significantly higher than that of elderly individuals. This results in a relatively lower percentage of body water in children compared to the correct answer, B.

C. Pregnant women: Although pregnant women have a higher body water content due to the increased volume of blood and amniotic fluid, the overall percentage of body water remains lower than in B.

D. Athletes: Athletes often have a higher lean mass and lower body fat percentage, leading to a higher percentage of body water in comparison to the correct answer, B, but not as high as in children.

**Clinical Pearls:**

1. In clinical practice, understanding the relationship between age and body water percentage is